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A245731 Number of connected labeled transitive relations on an n-set. 2
1, 2, 9, 109, 2647, 110481, 7291543, 726434549, 106312974249, 22465350835849, 6771847676632679, 2883916106465622053, 1720792953946798909927, 1427968172285571102335605, 1637002867699829205840095585, 2577011453377960519672777065693, 5541005747990556022043234479371823, 16195114271558690956785525865003941945, 64068293759315414337050896928055465961863 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..18.

FORMULA

E.g.f.: log(A(x + exp(x) - 1)) + 1 where A(x) is the e.g.f. for A001035.

EXAMPLE

a(2) = 9. There are 13 transitive relations on the set {1,2}. Four of these are not connected: {}, {(1,1)}, {(2,2)}, {(1,1),(2,2)}. 13-4=9.

CROSSREFS

Cf. A001035, A006905.

Sequence in context: A341056 A309452 A219116 * A290714 A062498 A339015

Adjacent sequences:  A245728 A245729 A245730 * A245732 A245733 A245734

KEYWORD

nonn

AUTHOR

Geoffrey Critzer, Jul 30 2014

STATUS

approved

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Last modified October 18 08:58 EDT 2021. Contains 348067 sequences. (Running on oeis4.)